1. Field of the Invention
Advanced high performance aircraft require an oxygen delivery system to supply breathing gas to aircraft crew members that is neither too high in oxygen content as to result in hyperoxia or too low so as to prevent hypoxia resulting in crew member fatigue or hyperventilation. Currently designed pneumatic regulators are not sufficiently accurate or responsive to changed conditions in the cabin causing excessive oxygen in the breathing mixture under some conditions and insufficient oxygen under others.
The present invention is a valve assembly for a dilution control oxygen regulator that responds to a command signal from a linear variable differential transducer that senses valve position and whose signal commands the valve to stop when valve position, corresponding to a desired oxygen-air concentration for the recipient's physiological needs, is attained.
2. Description of the Prior Art
Various patents have covered breathing supplies that are regulated by valves.
In U.S. Pat. No. 4,285,339 by McIntyre a demand servomechanism is used to regulate the supply of breathing gas supplied to a user. In McIntyre, the electrical signal is digitally processed and gas control valves are actuated by a "fast loop" electrical system. U.S. Pat. No. 4,352,352, Bolton et al discloses a respirator adapted to protecting the wearer against undesirable substances. U.S. Pat. No. 4,224,940 by Monnier discloses a respirator apparatus with a bellows that receives breathable gas from a suitable gas generator. U.S. Pat. No. 3,039,481 by Schreiber et al, discloses an apparatus with electromagnets for controlling the operating valves of a respirator. U.S. Pat. No. 3,610,237 by Barkalow et al, discloses a throttle valve operated by a spring-biased piston cylinder in a positive pressure breathing apparatus. However, none of the inventions disclose a valve control means with an analog design for controlling breathable gas which also uses a feedback transducer and a balance bellows as in the present invention.